Exhaust gases exit engine cylinders into an exhaust manifold. From the manifold, the exhaust gases are directed toward downstream exhaust system components such as the catalytic converter and muffler, for example. Double wall exhaust manifolds have been used in an attempt to maintain exhaust gas temperatures at the high levels needed for efficient operation of emission abatement devices such as the catalytic converter.
Double wall exhaust manifolds include an inner pipe configuration that is surrounded by an outer housing. The inner pipe directs the exhaust gases to downstream exhaust components and the outer housing is spaced from the inner pipe in portions to provide an insulating air gap.
In traditional double wall configurations the inner pipe is comprised of a plurality of inner components that are secured together and the outer housing is comprised of a plurality of outer components that are secured together to surround the inner pipe. This requires a significant number of components, which can increase cost and further results in a complex assembly process. Additionally, it is difficult to hold the inner pipe within the outer housing in a gas tight and stable manner.